A new method of terahertz difference frequency generation using periodically poled waveguide

Summary form only given. Several workers have demonstrated second harmonic generation in surface-emitting geometry. In this paper we suggest a method for THz region surface-emitting difference frequency generation (DFG) using periodically poled lithium niobate (PPLN) waveguide. It is shown that the PPLN waveguide is capable of emitting the difference frequency radiation in direction normal to the waveguide surface if the poling period is equal to L=/spl lambda//n/sub g/. Here /spl lambda/ is a wavelength of the emitted submillimeter radiation and n/sub g/ is a mean refractive index of the optical group velocity. In contrast to the optical waves, the PPLN structure with such period can be easily fabricated for THz waves.